The present invention relates to liquid chillers of the absorption type. More particularly, the present invention relates to a compact absorption chiller and a solution flow scheme therefor.
Absorption chillers are machines that by the use of chemical properties and reactions and pressure differentials caused thereby (among other things) provide a cooling effect that is typically employed to chill a liquid such as water. Absorption chillers are to be distinguished from so-called xe2x80x9celectric chillersxe2x80x9d which likewise produce chilled liquid but employ a compressor and a vapor compression process for purposes of chilling the liquid. The chilled liquid, in the case of both absorption and electric chillers, is most often used in the comfort conditioning of buildings or in manufacturing or industrial process applications.
Absorption chillers are often relatively very large and bulky pieces of equipment, weighing tens of thousands of pounds and occupying many hundreds if not thousands of cubic feet of space. Such chillers very often must be shipped internationally and to locations that can be tremendously difficult to access. Further, because absorption chillers have historically been relatively larger than electric chiller""s of the same capacity, absorption chillers have heretofore not generally been capable of being employed as direct replacements for electric chillers of the same capacity, most often due to space and/or access constraints associated with the location in which the electric chiller which is to be replaced is located.
One relatively recent attempt to address absorption chiller size issues can be found in the teaching of U.S. Pat. No. 5,259,205. That patent describes a modularized arrangement for an absorption chiller in which certain chiller elements can be horizontally or vertically stacked. The Background of the Invention portion of the ""205 patent accurately reflects and describes historical problems associated with absorption chillers in its reference to the fact that such machines, particularly those of xe2x80x9clarge-capacityxe2x80x9d, are often manufactured, charged with an absorbent and refrigerant, vacuum tested and factory test run to ensure the leak-tightness and satisfactory operation of the unit prior to shipment to their location of use.
The size of many such machines, however, often requires that the machine be cut or disassembled into component parts for shipment and be reassembled at the site of use. That process xe2x80x9cbreaksxe2x80x9d system integrity, can require significant amounts of welding in the field, often in difficult to access locations, and can be extremely detrimental to the cost, reliability, longevity and efficient operation of such units which can be contaminated in the process and which rely on vacuum tightness to properly function.
A modularized absorption chiller in the nature of the one of the ""205 patent is but one example of absorption chiller packaging for purposes of addressing the problems associated with the transport and handling of such chillers as well as an example of a solution flow scheme that is employed in conjunction with such a packaging concept to meet the requirements of the design. However, the need very clearly continues to exist for a still more compact design for an absorption chiller and a solution flow scheme therefor that is efficient and is capable of shipment throughout the world, preferably in commercially available, standardized shipping containers, as a non-modularized, pre-assembled, fully-charged, vacuum tested and operationally tested unit, and which need not be disassembled for shipment, even in relatively large chiller sizes/capacities.
It is an object of the present invention to provide a compact design for an absorption chiller which is applicable across a large range of chiller capacities.
It is another object of the present invention to provide an absorption chiller that employs a solution flow scheme that facilitates the compact packaging of an absorption chiller""s constituent components.
It is another object of the present invention to provide an absorption chiller in which, by the disposition of the low temperature generator vertically above the high temperature generator and by the use of a vertically split absorber/evaporator combination, overall chiller width is significantly reduced, even in chillers of relatively large capacity.
It is another object of the present invention to provide an absorption chiller design that is applicable across a relatively large range of capacities yet which is capable of fitting and being shipped, as a unit and without disassembly, within standard, commercially available shipping containers, irrespective of a particular capacity size within such range.
It is an additional object of the present invention to provide a design for an absorption chiller that is capable of being produced in capacities ranging up to at least 800 refrigeration tons that need not be disassembled or broken down for shipment in commercially available, standardized shipping containers.
It is a further object of the present invention to provide a direct-fired absorption chiller which, by the disposition of its constituent components and the solution flow scheme employed therewith, employs only a single pump for causing solution flow through the chiller.
It is another object of the present invention to provide an absorption chiller in which, by the arrangement of the constituent components thereof, gravity, elevational differences and pressure are employed to cause solution flow between certain ones of the chiller components with the result that chiller operation is achieved without the use of a booster pump.
It is a still another object of the present invention to provide a design for an absorption chiller and a solution flow scheme therefor which permits such chillers to be produced and shipped, without disassembly, in physical sizes that allow them to be used as replacements for electric chillers of the same capacity, even where such capacities extend to the 800 refrigeration ton capacity range.
It is a still further object of the present invention to provide for an absorber/evaporator arrangement in an absorption chiller which, by the reduction of vapor flow velocity/pressure drop between the chiller""s evaporator and absorber components, increases the heat transfer effectiveness of the chiller""s heat exchanger tube bundles and, as a result, overall chiller efficiency.
It is an additional object of the present invention to employ counterflow heat exchange relationships between cooling water and solution flow as well as the parallel and unmixed flow of concentrated solution at different temperatures to vertically split absorbers in an absorption chiller to enhance the efficiency of the chiller, to allow such chiller to function with a single solution pump, and without a booster pump, and to permit such chiller to physically fit within standardized shipping containers without the need to breakdown or disassemble the chiller for shipment, even in capacities as high as 800 refrigeration tons.
These and other objects of the present invention, which will be apparent when the following Description of the Preferred Embodiment and attached Drawing Figures are given consideration, are accomplished in an absorption chiller which employs vertically split and arranged high and low temperature absorber sections, together with counterpart vertically split evaporator sections, as well as a low temperature generator that is disposed vertically above the low temperature absorber and a high temperature generator disposed vertically below the high temperature absorber. Solution flow from the low temperature generator to the low temperature absorber is as a result of gravity and the elevational difference between those components. Solution flow from the high temperature generator to the high temperature absorber, which parallels the flow of the somewhat lower temperature concentrated solution from the low temperature generator to the low temperature absorber, is as a result of the pressure which is developed in the high temperature generator. The pressure in the high temperature generator is sufficient to drive the relatively higher temperature concentrated solution vertically upward and into the vertically elevated high temperature absorber. Because the high temperature absorber is elevated above the low temperature absorber, gravity is employed to deliver solution from the high temperature absorber to the low temperature absorber where the solutions flowing through those respective absorber sections mix and collect for use downstream in the chiller system.
By the employment of vertically split and arranged absorbers and associated split evaporator sections, the width of the absorber component of the chiller and the chiller overall is reduced sufficiently to permit it to be shipped as a unit in standardized shipping containers, without the need to disassemble or breakdown the chiller for shipment, even in the case of chillers of relatively very large capacity. As a result of the use of gravity and pressure to move solution between certain of the constituent components of the chiller, only one solution pump and no booster pump is required to achieve solution flow. Further, by the parallel and unmixed delivery and distribution of concentrated solution to the two absorber sections, where one of the flow streams of concentrated solution is hotter than the other, and by the counterflow of the chiller""s cooling medium through the chiller""s absorber section, maximum use is made of differential temperature, referred to as xe2x80x9ctemperature glidexe2x80x9d, within the chiller to enhance heat exchange and the overall efficiency of the chiller.